Saint Helena is a British Overseas Territory consisting of Saint Helena and Ascension Islands, and the island group of Tristan da Cunha. Saint Helena: Uninhabited when first discovered by the Portuguese in 1502, Saint Helena was garrisoned by the British during the 17th century. It acquired fame as the place of Napoleon BONAPARTE's exile, from 1815 until his death in 1821, but its importance as a port of call declined after the opening of the Suez Canal in 1869. During the Anglo-Boer War in South Africa, several thousand Boer prisoners were confined on the island between 1900 and 1903. Ascension Island: This barren and uninhabited island was discovered and named by the Portuguese in 1503. The British garrisoned the island in 1815 to prevent a rescue of Napoleon from Saint Helena and it served as a provisioning station for the Royal Navy's West Africa Squadron on anti-slavery patrol. The island remained under Admiralty control until 1922, when it became a dependency of Saint Helena. During World War II, the UK permitted the US to construct an airfield on Ascension in support of trans-Atlantic flights to Africa and anti-submarine operations in the South Atlantic. In the 1960s the island became an important space tracking station for the US. In 1982, Ascension was an essential staging area for British forces during the Falklands War, and it remains a critical refueling point in the air-bridge from the UK to the South Atlantic. Tristan da Cunha: The island group consists of the islands of Tristan da Cunha, Nightingale, Inaccessible, and Gough. Tristan da Cunha is named after its Portuguese discoverer (1506); it was garrisoned by the British in 1816 to prevent any attempt to rescue Napoleon from Saint Helena. Gough and Inaccessible Islands have been designated World Heritage Sites. South Africa leases a site for a meteorological station on Gough Island.